zobov: a parameter-free void-finding algorithm

Neyrinck, Mark C.

doi:10.1111/j.1365-2966.2008.13180.x

Cited by 345 publications

(443 citation statements)

References 43 publications

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“…It is part of the third generation of the SDSS (SDSS-III; Eisenstein et al 2011). We here briefly describe the void catalogue, based on the watershed and point-sample-based void finder ZOBOV (Neyrinck 2008). Greater detail can be found in Mao et al (2016).…”

Section: The Cmass Void Samplementioning

confidence: 99%

“…at around the 2σ level (Ilić et al 2013;Cai et al 2014;Planck Collaboration XIX 2014), or a null detection . All of these studies used the ZOBOV algorithm (Neyrinck, Gnedin & Hamilton 2005;Neyrinck 2008) to find voids. The variety of results reported by different groups is largely due to the differences in the way void catalogues are pruned.…”

Section: Introductionmentioning

confidence: 99%

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The lensing and temperature imprints of voids on the cosmic microwave background

Cai

Neyrinck

Mao

et al. 2016

Mon. Not. R. Astron. Soc.

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We have searched for the signature of cosmic voids in the CMB, in both the Planck temperature and lensing-convergence maps; voids should give decrements in both. We use ZOBOV voids from the DR12 SDSS CMASS galaxy sample. We base our analysis on N -body simulations, to avoid a posteriori bias. For the first time, we detect the signature of voids in CMB lensing: the significance is 3.2σ, close to ΛCDM in both amplitude and projected densityprofile shape. A temperature dip is also seen, at modest significance (2.3σ), with amplitude about 6 times the prediction. This temperature signal is induced mostly by voids with radius between 100 and 150 h −1 Mpc, while the lensing signal is mostly contributed by smaller voids -as expected; lensing relates directly to density, while ISW depends on gravitational potential. The void abundance in observations and simulations agree, as well. We also repeated the analysis excluding lower-significance voids: no lensing signal is detected, with an upper limit of about twice the ΛCDM prediction. But the mean temperature decrement now becomes non-zero at the 3.7σ level (similar to that found by Granett et al.), with amplitude about 20 times the prediction. However, the observed dependence of temperature on void size is in poor agreement with simulations, whereas the lensing results are consistent with ΛCDM theory. Thus, the overall tension between theory and observations does not favour non-standard theories of gravity, despite the hints of an enhanced amplitude for the ISW effect from voids.

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Section: The Cmass Void Samplementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The lensing and temperature imprints of voids on the cosmic microwave background

Cai

Neyrinck

Mao

et al. 2016

Mon. Not. R. Astron. Soc.

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“…More sophisticated algorithms find voids without making any assumption about their shape (e.g. Platen et al 2007;Neyrinck 2008). In the Local Universe, typical sizes of voids in the galaxy distribution vary from around 6 Mpc to more than 20 Mpc, in a galaxy survey like SDSS (e.g.…”

Section: Galaxy Population In Voidsmentioning

confidence: 99%

The galaxy population in cold and warm dark matter cosmologies

Wang

González-Pérez²,

Xie

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We use a pair of high resolution N-body simulations implementing two dark matter models, namely the standard cold dark matter (CDM) cosmogony and a warm dark matter (WDM) alternative where the dark matter particle is a 1.5 keV thermal relic. We combine these simulations with the GALFORM semi-analytical galaxy formation model in order to explore differences between the resulting galaxy populations. We use GALFORM model variants for CDM and WDM that result in the same z = 0 galaxy stellar mass function by construction. We find that most of the studied galaxy properties have the same values in these two models, indicating that both dark matter scenarios match current observational data equally well. Even in under-dense regions, where discrepancies in structure formation between CDM and WDM are expected to be most pronounced, the galaxy properties are only slightly different. The only significant difference in the local universe we find is in the galaxy populations of "Local Volumes", regions of radius 1 to 8Mpc around simulated Milky Way analogues. In such regions our WDM model provides a better match to observed local galaxy number counts and is five times more likely than the CDM model to predict subregions within them that are as empty as the observed Local Void. Thus, a highly complete census of the Local Volume and future surveys of void regions could provide constraints on the nature of dark matter.

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“…This is the criterion that we use to locate voids in the Lagrangian coordinates. We test our void finders using the catalogue of DM haloes extracted from a high-resolution N-body simulation (Baldi 2012) at z = 0, and compare our results with those obtained when we use the ZOBOV void finder (Neyrinck 2008). The quantitative comparison focuses on voids' statistics, as well as on physical properties such as their mass density profile and ellipticities.…”

Section: Introductionmentioning

confidence: 99%

“…The accuracy of the AP test has been discussed in comparison to that of other cosmological tests by . The first application of the method by Sutter et al (2012) considered voids extracted from the SDSS DR-7 galaxy survey (Abazajian et al 2009) using a modified version of the ZOnes Bordering On Voidness (ZOBOV) algorithm (Neyrinck 2008). With 10 stacked voids detected out to z = 0.36 they failed to detect any significant distortions.…”

Section: Introductionmentioning

confidence: 99%

Cosmic voids detection without density measurements

Elyiv

Marulli

Pollina

et al. 2015

Monthly Notices of the Royal Astronomical Society

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Cosmic voids are effective cosmological probes to discriminate among competing world models. Their identification is generally based on density or geometry criteria that, because of their very nature, are prone to shot noise. We propose two void finders that are based on dynamical criterion to select voids in Lagrangian coordinates and minimise the impact of sparse sampling. The first approach exploits the Zel'dovich approximation to trace back in time the orbits of galaxies located in voids and their surroundings, the second uses the observed galaxy-galaxy correlation function to relax the objects' spatial distribution to homogeneity and isotropy. In both cases voids are defined as regions of the negative velocity divergence, that can be regarded as sinks of the back-in-time streamlines of the mass tracers. To assess the performance of our methods we used a dark matter halo mock catalogue CoDECS, and compared the results with those obtained with the ZOBOV void finder. We find that the void divergence profiles are less scattered than the density ones and, therefore, their stacking constitutes a more accurate cosmological probe. The significance of the divergence signal in the central part of voids obtained from both our finders is 60% higher than for overdensity profiles in the ZOBOV case. The ellipticity of the stacked void measured in the divergence field is closer to unity, as expected, than what is found when using halo positions. Therefore our void finders are complementary to the existing methods, that should contribute to improve the accuracy of void-based cosmological tests.

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zobov: a parameter-free void-finding algorithm

Cited by 345 publications

References 43 publications

The lensing and temperature imprints of voids on the cosmic microwave background

The lensing and temperature imprints of voids on the cosmic microwave background

The galaxy population in cold and warm dark matter cosmologies

Cosmic voids detection without density measurements

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